The Centers for Disease Control and Prevention (CDC) currently conducts National HIV Behavioral Surveillance (NHBS) in 21 metropolitan statistical areas (MSA) in the U.S., including the Seattle MSA. We propose to continue NHBS in the Seattle MSA from 2011 to 2015. The goal of NHBS in the Seattle MSA is to provide relevant data for local HIV prevention resource allocation and prevention program evaluation. To accomplish this goal, we propose to collaborate with CDC to continue maintaining and evaluating a surveillance system of behaviors and co-infections related to HIV acquisition in men who have sex with men (MSM), injection drug users (IDU), and heterosexuals at increased risk (HET). Specifically, we will conduct formative research and community-based surveys and HIV testing each year. We will conduct a survey each year to assess HIV risk behaviors, HIV prevention services access and utilization, and HIV prevalence among Seattle-area MSM (2011 and 2014), IDU (2012 and 2015) and HET (2014). We will collaborate with Seattle area community-based organizations, public health department colleagues, University of Washington researchers with expertise in qualitative and quantitative methods to conduct NHBS and evaluate and disseminate results. We will employ venue-based time-space sampling (VBS) and respondent-driven sampling (RDS) and complete surveys with 500 eligible participants in each of the MSM and IDU cycles and 450 in the HET cycle. We will provide voluntary HIV counseling and testing to NHBS participants in all three cycles to assess HIV seroprevalence. We will conduct evaluations of the NHBS system including sampling strategies, and data collection methods to ensure that the system meets its goals, and provide recommendations for improving the quality, efficiency and usefulness of NHBS both locally and nationally. We will collaborate on development and implementation of local prevention survey questions with Seattle area community-based organizations that are directly funded by CDC or funded by state or local funding through the community planning process. We will contribute to the national data collections outcomes such as MMWR reports and other publications, and provide a data dissemination plan that will contribute to local and national surveillance reporting efforts. Finally, we will implement hepatitis C counseling and testing in the MSM and IDU cycles to assess hepatitis C seroprevalence. The Seattle area NHBS system will continue to be based at the HIV/STD Program of Public Health - Seattle &King County.